Transfer cases are used for distributing a driving torque produced by the driving unit of the motor vehicle to a number of outputs. Typically, transfer cases of this kind are used in motor vehicles with continuous or selectable all-wheel drive. They transfer the torque produced by the driving unit to two driven axles of the vehicle, and the distribution is predetermined or can be freely selected, depending on the construction of the transfer case. In order to be able to control the transmission of the torque to the two axles of the motor vehicle, a clutch unit is provided for example, offering the driver of the motor vehicle the possibility of choosing between a continuous two-wheel drive mode, in which the vehicle is driven exclusively via a primary axle, and an automatic four-wheel drive mode—referred to as an “on-demand drive mode”. In this mode, depending on the driving conditions, a certain proportion of the driving torque is transmitted to the wheels of the other axle (a secondary axle) in order to provide temporary four-wheel drive.
In principle, the transfer case can also be designed to include a controllable center differential, in which a clutch unit is provided to adjust the distribution of driving torque in the longitudinal direction of the vehicle.